The present invention relates generally to ink-jet printers, and, more particularly, to color ink-jet printers.
Ink-jet printers capable of forming color images using an ink set derived from cyan, yellow, magenta, and black inks are now commercially available. Ink-jet printers also are known to use additional, less concentrated cyan and magenta inks to smooth out tonal gradations. Specific types of ink-jet printers, such as thermal and piezoelectric, are also well-known.
U.S. Pat. No. 5,738,716 discloses 4-color pigment-based ink jet inks which exhibit color gamuts suitable for pictorial imaging with lightfastness. However these pigment-based ink sets are known to yield pale looking images when printed on absorbent media, such as fine art water color paper. Ink receiving coatings have been applied to enhance the color (U.S. Pat. No. 5,023,129), but the contrast of the image remains unacceptably low for high end pictorial imaging due to the lack of deep rich blacks.
Dye-based inks can be formulated which also exhibit improved lightfastness See for example U.S. Pats. Nos. 5,254,160; 5,725,641; 5,858,075; 6,113,677; 6,168,654; and 6,168,655. A well understood technique, by those skilled in the art, to improve dye-based inks"" lightfastness is to metalize the dye. But this results in less chromatic inks which makes it an undesirable solution for color inks such as cyan, magenta, yellow, red, green, and blue.
Thus, an object of the present invention is to provide an ink set that produces acceptably high contrast and high gamut pictorial images which are lightfast.